Texturing nozzle and method for the texturing of endless yarn

ABSTRACT

The invention relates to a method for the texturing of endless yarn by means of a texturing nozzle having a continuous yarn duct into which compressed air at a pressure higher than 4 bar is blown in the direction of the yarn conveyance, whereby the yarn duct is preferably conically widened at the outlet end with a widening angle larger than 10° for generating a supersonic flow. The invention furthermore relates to a texturing nozzle for the texturing of endless yarn with a continuous yarn duct having an inlet end, a central, preferably cylindrical portion with an air supply orifice as well as a preferably conical outlet end with a widening angle larger than 10°, but smaller than 40°.

TECHNICAL FIELD

The novel invention relates to a method for the texturing of endlessyarn by means of a texturing nozzle having a continuous yarn duct intowhich compressed air at a pressure of more than 4 bar is blown in thedirection of the yarn conveyance, whereby the yarn duct is preferablyconically widened at the outlet end with a widening angle larger than10° for generating a supersonic flow. The invention further relates to atexturing nozzle for the texturing of endless yarn with a continuousyarn duct having an inlet end, a central—preferably cylindrical—portionwith an air supply orifice as well as an outlet end with a wideningangle larger than 10°.

STATE OF THE ART

The term texturing is partly still understood as the processing of spunfilament bundles and the corresponding endless yarns, respectively, withthe aim of rendering a textile character to the yarn. In the followingdescription, the term texturing shall designate the generation of amultitude of loops on single filaments and the production of loop yarn,respectively. An older solution for texturing is described in the EP 0088 254. The endless filament yarn is supplied to the yarn driving ductat the inlet end of a texturing nozzle and textured at a trumpet-shapedoutlet end through the forces of a supersonic flow. The central portionof the yarn driving duct is of a continuous cylindrical shape with aconstant cross section. The inlet is slightly rounded for a smoothsupply of the untreated yarn. At the trumpet-shaped outlet end there isan impact member, whereby the looping takes place between thetrumpet-shape and the impact member. The yarn is fed to the texturingnozzle at high excess delivery. The excess delivery is required for thelooping on each individual filament causing an increased titer at theoutlet end.

The EP 0 088 254 was based on a device for texturing at least oneendless yarn consisting of a multitude of filaments with a nozzlecharged with a compressed medium, having a yarn driving duct as well asat least one admission for the compressed medium discharging into theduct in radial direction. The generic nozzle had an outlet of the ductwidening in external direction and an impact member in the shape of aball and a hemisphere, respectively, protruding into the duct andforming an annular gap with the latter. It was noted that for texturedyarns the preservation of the yarn features both during and after theprocessing procedure for the finished product is an important criterionfor possible uses of such yarns. Moreover, the extent of the degree ofmixing of two or more yarns and of the individual filaments of texturedyarns is also of essential importance for obtaining a uniform appearanceof the product. In this context, the stability is a quality standard.The instability of the yarn is determined by forming small hanks of yarnwith four coils having a circumference of one meter each on a reel, asexplained by means of a multifilament yarn for polyester of the titer167f68 dtex. These small hanks are then subjected to a test load of 25cN for one minute and the length X is measured. The yarn is subsequentlysubjected to a test load of 1250 cN for another minute. After relievingthe load for one minute, the small hank is again subjected to a load of25 cN and after another minute the length Y is measured. This providesthe value for the instability:

$I = {{\frac{Y \cdot X}{X} \cdot 100}\%}$

The instability indicates the percentage of lasting stretching caused bythe applied load. The EP 0 088 254 dealt with the task of providing animproved device of the described type with which an optimum texturingeffect can be achieved which ensures a high stability of the yarn and ahigh degree of mixing of the individual filaments. As a solution it wasproposed that the outer diameter of the convexly curved outlet apertureof the duct is at least equivalent to the fourfold of the diameter ofthe duct and at least equivalent to the 0.5-fold of the diameter of theball- or hemisphere-shaped impact member (5). Optimum results wereobtained for production rates in the range between 100 and more than 600m/min. Interestingly, the applicant successfully marketed correspondingnozzles for more than 15 years. The quality of the yarn manufacturedwith these nozzles was assessed as very good for a period of 1½ decades.Increasingly, however, an improved performance was desired. Theapplicant managed with the solution in accordance with the EP 0 880 611to obtain a massively improved performance of a yarn conveyance rate ofup to much more than 1000 m/min. The central concept for the increase inperformance resided in the intensification of the flow conditions in thewidening supersonic duct, i.e. in the zone in which the looping takesplace. The yarn tension at the outlet of the texturing nozzle wasidentified as a specific test criterion. Many test series revealed thatfor the solution in accordance with the EP 0 088 254, the yarn tensionconsiderably decreases for a yarn conveyance rate above 600 m/min. Thisis eventually the explanation for the performance limit of these typesof nozzle.

The intensification of the flow in the supersonic duct proposed in theEP 0 880 611 provided an unexpected rise in the yarn tension, whichallowed an increase of the conveyance speed to more than 1000 m/min. Thequality of the processed yarn was initially evaluated as identical ifnot better including for highest conveyance rates. However practicalexperience has later shown surprises insofar as that in manyapplications the quality of the yarn did not meet desired requirements.

The task of the novel invention has now been to develop a method and atexturing nozzle which allow for an increase in performance inparticular well above 1000 m/min, but at the same time provide highestyarn qualities in all areas of applications if possible.

DESCRIPTION OF THE INVENTION

The method in accordance with the invention is characterized in that thecompressed air for an intensified opening of the yarn is supplied to theyarn duct at a supply angle of more than 48°, in particular more than50°.

All previous examinations could only confirm that for data establishedwith texturing nozzles in accordance with the EP 0 088 254 the optimumsupply angle for the treatment air is at 48°. Any increase beyond 48°only caused a deterioration of the texturing. In this respect, referenceis also made to the large-scale examination of A. Demir in the “Journalof Engineering for Industry” of February 1990 (vol. 112/97). The authorof the article had the opportunity to test the essential parameters inmany test series. Nozzles with supply angles of 30°, 45° and 60° weretested in these series. The performance of nozzles with supply angles of60° was poor in several aspects, not last because at 60° a large part ofthe energy impacts on the opposite wall and is destroyed. This providedthe scientific corroboration of what had been found empirically in thecourse of the development of the texturing nozzle in accordance with theEP 0 088 254 and had no longer been doubted subsequently. For thedevelopment of the new nozzle shape in accordance with the EP 0 880 611there was no reason to doubt the opinion of experts, which had beenfirmly established over the years, i.e. that the range between 45° and48° represented an optimum supply angle. This characteristic was hencealso reflected in the description of the solution in accordance with theEP 0 880 611.

As already discussed, in the context of efforts at improving yarnqualities, a new attempt was made i. a. as regards the influence of thesupply angle. As a complete surprise it was noted that the expansion ofthe supply angle with nozzles in accordance with the EP 0 880 611provided already in the first test series an unexpected increase inquality of the textured yarn. Subsequently, the inventors observed thatthe two process zones of

-   -   opening the yarn, and    -   texturing the yarn        need to be optimally geared to one another. Repeated tests        showed that for the solution in accordance with the EP 0 880 611        the limitation rests with the texturing zone and that        consequently an increase of the yarn opening is only        disadvantageous. It is known from the area of yarn intermingling        that the effect of the yarn opening is largest at a supply angle        of 90°. The objective of intermingling is to form regular knots        in the yarn. Reference is made to the DE 195 80 019 which gives        an example for intermingling. For textured yarn, however, knots        may not be formed at any circumstance. There must be a limit        zone for the supply angle for the two basically different        methods of knot formation and looping. However, these limits        could not yet be determined. To date a range for the supply        angle is assumed between 49° and 80°, preferably between 50° and        about 70°. The upper limit could not yet be definitely        established. The yarn duct has a central, preferably cylindrical        portion, which continues smoothly into the conical widening in        the direction of conveyance, whereby the compressed air is        supplied in a sufficient distance to the conically widened        supersonic duct in the cylindrical portion.

The tests conducted in connection with the novel invention essentiallyprovided the following three findings.

-   -   For texturing nozzles with intensified supersonic flow in        accordance with the EP 0 880 611 an improved quality was        obtained for each yarn titer if the supply angle was raised over        48°.    -   The increase in quality starts with a marked rise as the angle        is increased over 48°.    -   For supply angles exceeding 52°, partly up to 60° and even 65°,        the yarn quality remains remarkably constant. The optimum supply        angle depends, however, also on the yarn titer.

It is therefore proposed to fix the supply angle as a function of theyarn quality, in particular of the yarn titer, in the range between 48°and 80°, preferably between 50° and 70°. The advantages of the novelinvention can be exploited with texturing nozzles having only a singleorifice through which the compressed air is supplied at an angleexceeding 48° and 50°, respectively. It is, however, preferred to havethe compressed air supplied to the yarn duct through three orificesstaggered in the circumference by 120°. In any case it is decisive thatthe opening of the yarn is intensified by supplying the compressed airto the yarn duct, but that a formation of knots in the yarn is avoided.

The texturing nozzle in accordance with the invention is characterizedin that the compressed air for the intensification of the yarn openingis supplied to the yarn duct in a supply angle of more than 48°,preferably 50°. Preferably, the air supply location is arranged in thecylindrical portion with a distance to the conical widening, whereby thedistance is at least equivalent to the diameter of the yarn duct.Pursuant to the current knowledge, the length of the two process stages,i.e. opening and texturing, is too short for nozzles in accordance withthe older the EP 0 088 254. This is one of the reasons for the limitedconveyance rate achieved with a type of nozzle in accordance with theolder solution.

The novel invention established various findings:

-   1. The opening of the yarn on the one hand and the texturing of the    yarn on the other must be optimized individually.-   2. In order to optimize these two completely different functions    they must be conducted at separated locations,-   3. but one shortly after the other, such that the opening takes    place immediately prior to the texturing and that the completion of    the yarn opening process immediately blends over into the texturing,    respectively.

At least the central cylindrical portion as well as the conicallywidened outlet portion of a texturing nozzle are provided as part of thenozzle core. The nozzle core is preferably provided as an insert insidea texturing nozzle head and made of a material resistant to wear, inparticular ceramic.

It is particularly advantageous if the nozzle core is provided as aremovable core such that a nozzle core with optimum internal dimensionsand inlet angles can be inserted. This allows e.g. removal of anexisting state-of-the-art nozzle core by a few manipulations and use ofall advantages of the novel invention. At the outlet end of theconically widened portion an impact member is arranged as with the stateof the art, which can be adjusted at least closely to the conicallywidened outlet portion. This further contributes to the constancy of theyarn quality. The texturing nozzle is advantageously provided as a partof the texturing head, whereby the air distribution is arranged on threeair supply orifices in the texturing head. Hereinafter, reference ismade to the EP 0 880 611, which is the basis and starting point for thenovel invention insofar as the process stage of texturing is concerned.

It was found in the EP 0 880 611 that the key to quality resides in theyarn tension after the texturing nozzle. The quality can be improvedonly if the yarn tension is increased. The breakthrough was possiblewhen the flow of the air jet was increased above the range of Mach 2.Numerous test series confirmed that not only the quality is improved butalso the quality is adversely affected to an amazingly small extent byan increase in the production rate. Already a slight increase in theMach number above 2 produced significant results. The best explanationof the corresponding intensification of the texturing process resides inthe fact that the difference in the rate is increased directly beforeand after the shock wave, which directly affects the correspondingforces of action by the air on the filaments. The increased forces inthe area of the shock wave cause an increase in the yarn tension. Theaction at the shock wave is increased directly by raising the Machnumber. In accordance with the invention the following rule wasrecognized: higher Mach number=stronger shock=more intense texturing.The intensified supersonic flow grasps the individual filaments of theopened yarn over a broader front and much more intensely, such that noloops can escape laterally beyond the zone of action of the shock wave.As the production of the supersonic flow in the acceleration duct isbased on expansion, an increase and almost a doubling of the effectiveoutlet cross section is obtained as a result of the higher Mach range,for instance Mach 2.5 instead of Mach 1.5. Various surprisingobservations were made, which were also confirmed in combination withthe novel invention:

-   -   When using a supersonic duct designed for the higher Mach range,        a qualitative improvement in texturing occurred—as compared to        the prior art—at an identical production rate.    -   Tests with individual yarn titers were carried out up to a        production rate of 1,000 to 1,500 m/min without a breakdown of        texturing.    -   By measurement it was noted immediately that the yarn tension        could be increased by an average of about 50%. The increased        value also remained almost constant over a great speed        range e. g. between 400 and 700 m/min.    -   It was also established that the choice of the supply pressure        of the compressed air is a significant influencing factor. A        higher supply pressure is required in many cases to ensure the        higher Mach numbers. This is normally between about 6 and 14        bar, can however also be increased to 20 bar and above.

The comparison tests, state of the texturing art in accordance with theEP 0 088 254 and a novel solution pursuant to the EP 0 880 611 provedthe following rule in a remarkably wide range: The quality of texturingis at least equal if not better with a supersonic duct designed for thelower Mach range at a higher production rate as compared to the qualityof texturing at a lower production rate. The texturing process is sointense at air speeds in the shock wave higher than Mach 2, e. g. atMach 2.5 to Mach 5, that even at maximum yarn passage rates all loopsare adequately picked and bound well into the yarn almost withoutexception. The generation of an air speed in a high Mach range has theeffect within the acceleration duct that texturing no longer breaks downincluding at maximum speeds. Secondly the entire filament assembly isguided uniformly and directly into the shock wave within clear outerduct delineations. The actual focal criterion for the positive effect ofthe novel invention resides in the fact that the stability of the yarnis generally improved. If a strong tensile force is applied to and takenaway from the yarn textured in accordance with the new solution, it isnoted that the texture, i. e. the firm assembly locations and loops, ispreserved almost unchanged. This is a decisive factor for the subsequentprocessing.

In the acceleration duct the yarn is drawn in by the accelerating airflow via the corresponding path in the acceleration duct, opened furtherand transferred to the adjacent texturing zone. The air jet is thenguided to the acceleration duct without deflection through anirregularly and markedly widening portion. One or more yarn filamentscan be introduced with identical or different excess delivery andtextured at a production rate between 400 and above 1,200 m/min. Thecompressed air jet in the supersonic duct is accelerated to between 2.0and 6 Mach, preferably to between 2.5 and 4 Mach. The best results areachieved when the outlet end of the yarn duct is limited by an impactmember such that the textured yarn is discharged through a gap roughlyat a right angle to the axis of the yarn duct.

Particularly preferably the air jet is guided including for the novelinvention pursuant to the radial principle from the feed location into acylindrical portion of the yarn duct directly in an axial direction at aroughly constant speed to the acceleration duct. As in the state of theart of the EP 0 880 611, one or more yarn filaments can also be texturedwith the most varied excess delivery with the novel method. The totaltheoretically effective widening angle of the supersonic duct from thesmallest to the largest diameter should preferably be greater than 10°but smaller than 40°, preferably within the range between 15° and 30°.The currently available roughness values have led to an upper limitangle (total angle) between 35° and 36° in the production of series. Thecompressed air is accelerated substantially steadily in a conicalacceleration duct. The nozzle duct portion immediately before thesupersonic duct is preferably substantially cylindrical in design, airbeing supplied into the cylindrical portion with a conveying componentin the direction toward the acceleration duct. The intake force on theyarn is increased with the length of the acceleration duct. The nozzlewidening and the increase of the Mach number, respectively, provides theintensity of texturing. The acceleration duct should at least have across-sectional enlargement range of 1:2.0, preferably 1:2.5 or greater.It is further proposed that the length of the acceleration duct be 3 to15 times, preferably 4 to 12 times greater than the diameter of the yarnduct at the beginning of the acceleration duct. The acceleration ductcan be widened completely or partially steadily, can have conicalportions and a slightly spherical shape, respectively. However, theacceleration duct can also be designed in fine steps and have differentacceleration zones having at least one zone with a high acceleration andat least one zone with a low acceleration of the compressed air jet. Theoutlet area of the acceleration duct can also be cylindrical orapproximately cylindrical and the inlet area can be markedly widened,but the widening will be less than 36°. If the marginal conditions forthe acceleration duct are maintained in accordance with the invention,said variations in the acceleration duct have proven to be almostcorresponding or at least equivalent. Behind the supersonic duct, theyarn duct has a markedly convex yarn duct mouth which is preferablywidened by more than 40° in the form of a trumpet, whereby thetransition from the supersonic duct into the yarn duct preferably runsunsteadily. A decisive factor was found to reside in the fact that thepressure conditions in the texturing chamber can be positivelyinfluenced and can be kept stable in particular with an impact member. Apreferred embodiment of the texturing nozzle in accordance with theinvention is characterized in that it has a continuous yarn duct with acentral cylindrical portion into which the air supply opens and, in thedirection of yarn travel, a conical acceleration duct immediatelyfollowing the cylindrical portion, with an opening angle (α₂) greaterthan 15°, as well as an adjacent widening portion with an opening angle(δ) greater than 40°.

BRIEF DESCRIPTION OF THE INVENTION

Further details of the invention are now described by means of severalembodiments.

FIG. 1 shows the yarn duct in the area of the yarn opening and texturingzone in accordance with the novel invention.

FIG. 2 shows a schematic representation of the yarn tension test duringtexturing.

FIG. 3 shows a nozzle core in accordance with the invention in a largerscale.

FIG. 4 shows a nozzle core with an impact member at the outlet of theacceleration duct.

FIG. 5 shows a complete nozzle head with an impact member.

FIG. 6 shows a comparison of textured yarn pursuant to the state of theart with the novel invention as related to the yarn tension.

FIG. 7 a through 7 c and FIG. 8 a through 8 c show the test results asrelated to various supply angles base on a nozzle in accordance with thestate of the art having a supply angle of 48°.

FIG. 9 shows the use of a thermal stage in combination with texturing.

FIG. 10 a through 10 d show the thermal use over heated godets.

METHODS AND IMPLEMENTATION OF THE INVENTION

Reference will be made hereinafter to FIG. 1. The texturing nozzle 1presents a yarn duct 4 having a cylindrical portion 2 which at the sametime corresponds to the narrowest cross section 3 with a diameter d.From the narrowest cross section 3 the yarn duct 4 continues without asudden change in the cross section into an acceleration duct 11 and isthen widened in the shape of a trumpet, whereby the trumpet shape can bedefined with a radius R. A corresponding shock wave diameter DA_(E) canbe determined on the basis of the prevailing supersonic flow. Theremoval or cessation location A₁, A₂, A₃ or A₄ can be determinedrelatively exactly on the basis of the shock wave diameter DA_(E). Asfor the effect of the shock wave, reference is made to the EP 0 880 611.The acceleration area of the air can also be defined by the length l₂from the location of the narrowest cross section 3 and the cessationpoint A. As this is a genuine supersonic flow, the air speed can becalculated roughly from it.

FIG. 1 shows a conical embodiment of the acceleration duct 11 whichcorresponds to the length l₂. The opening angle. α₂ is given at about20°. The removal location A₂ is indicated at the end of the supersonicduct, where the yarn duct passes into the unsteady, markedly conical ortrumpet-shaped widening 12 with an opening angle δ>40°. The shock wavediameter D_(AE) can be determined geometrically. As an example thefollowing equations are roughly obtained:

${{{L2}\text{/}d} = 4.2};{{Vd} = {330\mspace{14mu} m\text{/}{\sec.\mspace{11mu}\left( {{Mach}\mspace{14mu} 1} \right)}}};{\left. {\frac{DAE}{d} \sim 2.5}\rightarrow M_{DE} \right. = {{Mach}\mspace{14mu} 3.2}}$

An extension of the acceleration duct 11 with a corresponding openingangle increases the shock wave diameter D_(AE). The maximum compressionshock wave 13 occurs directly in the area of shock wave formation with asubsequent abrupt pressure increase zone 14. The actual texturing takesplace in the area of the compression shock wave 13. The air moves fasterthan the yarn roughly by the factor 50. It was possible to determine bymany experiments that the removal location A₃, A₄ can also travel intothe acceleration duct 11, namely when the supply pressure is reduced. Inpractice, the optimum supply pressure has to be determined now for eachyarn, the length (l₂) of the acceleration duct being designed for themost undesirable case, and is therefore selected rather too long. M_(B)designates the central line of the inlet orifice 15, and M_(GK) thecentral line of the yarn duct 4, and SM the intersection point of M_(GK)and M_(B). Pd is the location of the narrowest cross section at thebeginning of the acceleration duct 11, l₁ is the distance between SM andPd, l₂ is the distance between Pd and the end of the acceleration duct(A4). Löff designates roughly the length of the yarn opening zone, Ltexroughly the length of the yarn texturing zone. The wider angle β, thelarger the rearward expansion of the yarn opening zone.

FIG. 2 shows a complete texturing head or nozzle head 20 with built-innozzle core 5. The unprocessed yarn 21 is supplied to the texturingnozzle 1 via a delivery mechanism 22 and is forwarded as textured yarn21′. An impact member 23 is located in the outlet area 13 of thetexturing nozzle. A compressed air connection P′ is arranged laterallyon the nozzle head 20. The textured yarn 21′ travels at a conveying rateVT via a second delivery mechanism 25. The textured yarn 21′ is guidedvia a quality sensor 26, e.g. with the trade name HemaQuality, known asATQ, in which the tensile force of the yarn 21′ (in cN) and thedeviation of the instantaneous tensile force (sigma %) are measured. Themeasurement signals are supplied to a computer 27. The correspondingquality measurement is a condition for the optimum monitoring of theproduction. The values are also an indicator of the yarn quality.Quality determination is particularly difficult in the air jet texturingprocess in so far as there is no defined loop size. It is much better todetermine the deviation from the quality a customer considers good. Thiscan be performed with the ATQ system because the yarn structure and thedeviation thereof can be determined and evaluated via a yarn tensionsensor 26 and can be displayed by a single characteristic, the AT value.A yarn tension sensor 26 detects in particular the tensile force of theyarn after the texturing nozzle as an analog electric signal. The ATvalue is determined continuously from the mean value and variance of themeasured values of the tensile force of the yarn. The size of the ATvalue is dependent on the structure of the yarn and is determined by theuser according to his own quality requirements. If the tensile force ofthe yarn or the variance (uniformity) of the yarn tension varies duringproduction, the AT value also varies. Upper and lower limit values canbe determined by yarn levels and samples of knit or woven fabric. Theydiffer according to quality requirements. The advantage of the ATQmeasurement resides in the fact that various disturbances of the processcan be detected simultaneously, e. g. regularity of texturing, yarnwetting, filament breakages, nozzle contamination, impact memberdistance, hotpin temperature, air pressure differences, POY insertionzone, yarn presented, etc.

Reference will be made hereinafter to FIG. 3 which shows a stronglymagnified preferred embodiment of a complete nozzle core 5 in a crosssection. The outer fitting shape is preferably adapted exactly to thestate-of-the-art nozzle cores. This applies in particular to thecritical installation dimensions, the orifice diameter B_(D), the totallength L, the nozzle head height K_(H) as well as the distance L_(A) forthe compressed air connections PP′. The tests have shown that theoptimum intake angle β has to be greater than 48°. The distance X of thecorresponding compressed air orifices 15 is critical as related to theacceleration duct. The yarn duct 4 has a yarn inlet cone 6 in the yarninlet area, arrow 16. The outgoing air flow directed backwards isreduced by the compressed air directed in the sense of the yarnconveyance (arrow 16) via the oblique compressed air orifices 15. Thedimension “X” (FIG. 6) indicates that the air orifice is set backpreferably at least roughly by the size of the diameter d of thenarrowest cross section 3. Viewed in the conveying direction (arrow 16),the texturing nozzle 1 and the nozzle core 5, respectively, has a yarninlet cone 6, a cylindrical central portion 7, a cone 8, whichsimultaneously corresponds to the acceleration duct 11, and a widenedtexturing chamber 9. The texturing chamber is delineated transversely tothe flow by a trumpet shape 12, which can also be designed as an openconical funnel. FIG. 3 shows a texturing nozzle with three compressedair orifices 1, which are staggered by 120° each and open to the samelocation Sm in the yarn duct 4.

FIG. 4 show a nozzle core 5 with an impact body 14 strongly magnified ascompared to the actual size. The novel nozzle core 5 can be designed asa replacement core for the previous art. In particular the dimensionsB_(d), E_(L) as the installation length, L_(A)+K_(H) as well as K_(H)are therefore preferably manufactured not only equal, but also havingthe same tolerances. Furthermore, the trumpet shape is preferably alsoproduced identically in the external outlet area to the state of the artwith a corresponding radius R. The impact member 14 can be of any shape:spherical, flat ball-shaped or even in the form of a cap. The exactposition of the impact member in the outlet region is retained bymaintaining the external dimensions, corresponding to an identicaltake-off gap S_(p1). The texturing chamber 18 remains externallyunchanged, but is now directed backwards and defined by the accelerationduct 11. The texturing chamber can also be enlarged into theacceleration duct, depending on the value of the selected air pressure.As with the state of the art, the nozzle core 5 is produced from ahigh-quality material such as ceramic, hard metal or special steel andis actually the expensive part of a texturing nozzle. It is importantwith the novel nozzle that the cylindrical wall surface 21 as well asthe wall surface 22 is of optimum quality in the area of theacceleration duct. The constitution of the trumpet-shaped widening isdetermined with regard to yarn friction.

FIG. 5 shows a complete nozzle head 20 with a nozzle core 5 as well asan impact member 14, which is adjustable by an arm 27 and secured in aknown housing 28. For threading purposes, the impact member 14 is drawnand swung away, respectively, with the arm 27 from the working area 30of the texturing nozzle in a known manner as indicated by arrow 29. Thecompressed air is supplied from a housing chamber 31 via compressed airorifices. The nozzle core 5 is firmly clamped on the housing 33 by aclamping member 32. Instead of a ball shape, the impact member can alsohave a cap shape.

The bottom left-hand corner of FIG. 6 shows the state-of-the-arttexturing in accordance with the EP 0 088 254 purely schematically. Twomain parameters are emphasized: An opening zone Oe-Z₁ as well as a shockwave diameter DAs, starting from a diameter d corresponding to a nozzledescribed in the EP 0 088 254. On the other hand the texturing inaccordance with the EP 0 880 611 is shown in the top right-hand corner.It can be seen very clearly that the values Oe-Z₂ as well as D_(AE) aregreater. The yarn opening zone Oe-Z₂ begins shortly before theacceleration duct in the area of the compressed air supply P and isalready markedly greater as related to the relatively short yarn openingzone Oe-Z₁ of the solution in accordance with the EP 0 088 254.

The essential message of FIG. 6 resides in the diagrammatic comparisonof the yarn tension in accordance with the state of the art (curve T311) with Mach<2 and a texturing nozzle in accordance with the invention(curve S 315) with Mach>2 as well a the novel nozzle. The verticalcolumn of the diagram shows the yarn tension in CN. The horizontal linedepicts the production rate Pgeschw. in m/min. The curve T 311 shows theclear collapse of the yarn tension above a production rate of 500 m/min.Texturing conducted with the nozzle in accordance with the EP 0 088 254broke down above about 650 m/min. In contrast, curve S 315 with thecorresponding nozzle in accordance with the EP 0 880 611 shows that theyarn tension is not only much higher but is almost constant in the rangebetween 400 and 700 m/min and decreases only slowly even in the higherproduction range. The increase of the Mach number is one of the mostimportant parameters for the intensification of the texturing. Theincrease of the supply angle is one of the most important parameters forthe quality of texturing, which is depicted as a third example with thenovel nozzle in the top left-hand corner. As an example the supply angleis indicated in the range between 50° and 60°. The yarn opening zoneOe-Z₃ is greater than the one in the solution in the top right-handcorner (in accordance with the EP 0 880 611) and substantially greaterthan in the solution in the lower left-hand corner (in accordance withthe EP 0 088 254). The other procedural parameters of the method areidentical for all three solutions. Besides the different supply angle inthe range between 45° and 48° and new above 45°, the surprisinglypositive effect is found in the first portion of the yarn opening zone,such as OZ₁ and OZ₂ and as marked in the corresponding circle,respectively. As depicted in FIGS. 7 and 8, the external differenceexclusively resides in the changed supply angle. The marked increase ofthe yarn tension starts at an angle of more than 48° and can only beexplained by a combinatory effect. In so far as the surprisinglypositive effect is currently understood, a supply angle of 48°represents a threshold, but only with texturing nozzles in accordancewith the EP 0 880 611. This type of texturing nozzle has a sufficientperformance reserve such that even a slight intensification of the yarnopening is translated into an increased yarn quality.

The FIGS. 7 a through 7 c and 8 a through 8 c show diagrammatically therelations of various parameters related to the state of the art (T341 K₁as well as S345) as well as the texturing nozzles in accordance with theinvention with supply angles between 50° and 58°. In FIG. 8 a, the yarntension increases from left to right markedly strongly from some 20 cNto 56 cN. In the example portrayed, the yarn tension is more thandoubled on average with the novel invention. FIG. 7 a shows a yarntension that initially increases less markedly. To date all tests haveled to variations for the two diagrams 7 a and 8 a and hence to thefinding that the yarn tension is markedly greater above a supply angleof 48°. Both FIG. 7 c and 8 c show three differently textured yarnpatterns each. The upper yarn patterns were produced with nozzles inaccordance with the state of the art, the uppermost pursuant to the EP 0088 254 (T-nozzle) and the middle one pursuant to the EP 0 880 611(S-nozzle). The patterns in the bottom part were produced with texturingnozzles in accordance with the novel invention. Relatively widelyprotruding loops with a lack of compact sections are noted immediatelyfor the yarn patterns produced pursuant to the state of the art. Thedimension B₁ and B₂ indicates the size of the distance for the mostprotruding loops. For the two lower yarn patterns, the dimension B₃ issubstantially smaller. In particular, however, very compact sections andstill relatively dense sections with many loops are noted in shortsequence. But the essential aspect resides in the fact that the yarnpatterns react extremely different under a load. If the yarn patterns inaccordance with the state of the art (top and center) are placed under atensile stress, the loops open too much and do not form again once thetensile stress is removed. In contrast the loops in the yarn patterns inaccordance with the novel invention remain almost fully intact includingafter removal of the tensile stress. This means that the quality oftexturing had been noticeably increased in a twofold way, a fact thatwas confirmed with all yarn titers tested so far. Moreover it is aninteresting fact that it was possible to confirm the correspondingincrease in quality and performance including with the novel inventionwhen a thermal effect in accordance with the WO99/45182 was applied. TheEP 1 058 745 is declared an integral part for the correspondingadditional combinatory effect.

Reference will be made hereinafter to FIG. 9, which shows a schematicoverview related to the novel texturing method. From top to bottom theseparate procedural stages are represented sequentially. Smooth yarn 100is guided to a texturing nozzle 101 and through the yarn duct 104 fromthe top via a first delivery mechanism LW1 at a conveyance rate V1.Highly compressed air, preferably not heated, is supplied at an angle αin the direction of conveyance of the yarn into the yarn duct viacompressed air ducts 103 connected to a compressed air source P1.Immediately following, the yarn duct 104 is conically opened such thatin the conical portion 102 a massively accelerated supersonic air flow,preferably at more than Mach 2, is generated. The shock waves create—asdescribed in detail in the WO97/30200 mentioned above—the actualtexturing. The first portion from the air supply location 105 into theyarn duct 104 through to the first portion of the conical widening 102serves for the loosening and opening of the smooth yarn such that theindividual filaments are subjected to the supersonic flow. Depending onthe size of the available air pressure (9 . . . 12 up to 14 bar andmore) the texturing takes place either yet inside the conical portion102 or in the outlet area. There is a direct proportionality between theMach number and the texturing. The larger the Mach number, the higherthe shock effect and the more intense the texturing. Two criticalparameters were noted for the production rate:

-   -   the desired quality standard, and    -   the trembling, which can cause the texturing to collapse, if the        conveyance rate is further increased.

The following abbreviations are used:

-   Th.vor. Thermal pre-treatment, possibly only by heating the yarn or    by using hot vapor.-   G.mech. Treatment of the yarn with the mechanical effect of a    compressed air flow (supersonic flow).-   Th.nach. Thermal post-treatment with hot vapor (possibly only heat    and hot air, respectively).-   D. Vapor-   PL. Compressed air.

It was possible, by additional thermal treatment, to increase theproduction rate to up to 1500 m/min without a collapse of the texturingand without trembling, whereby the existing test system was the limitingcondition. Best texturing qualities were obtained at production ratesmuch higher than 800 m/min. Surprisingly, the inventors discovered oneand two completely new quality parameters, respectively, whereby alltests only confirmed the rule mentioned above (higher Machnumber=stronger surge=more intense texturing). On the one hand thediscovered parameters reside in a heat treatment before and after thetexturing, respectively, and—on the other—in an increase of the Machnumber by raising the air pressure as well as a corresponding design ofthe acceleration duct.

-   -   a) Thermal post-treatment or relaxation        -   Specialists consider the yarn tension of the yarn leaving            the texturing nozzle an important quality criterion for            texturing, which is also recognized as a measure for the            intensity of the texturing. The yarn tension on the textured            yarn 106 is generated between the texturing nozzle (TD) and            the delivery mechanism LW2. A thermal treatment of the yarn            subjected to a tensile stress was conducted in this area            between texturing nozzle (TD) and delivery mechanism LW2. In            this process the yarn was heated to some 180° C. First tests            could already be completed successfully both with a hotpin            or a heated godet and also with a hotplate (contact-free),            with the surprising result that the quality limit related to            the conveyance rate could be massively increased. At present            it is assumed that the described thermal post-treatment has            a fixing and simultaneously a shrinking effect on the            textured yarn and thereby supports the texturing.    -   b) Thermal pre-treatment        -   Much more surprisingly, the thermal pre-treatment similarly            had a positive effect on the texturing process. Here the            cause for success is deemed to be a combinatory effect of            shrinking and yarn opening in the portion between the air            supply location in the yarn duct and the first part of the            conical widening in the area of the supersonic speed. The            stiffness is reduced by warming up the yarn which improves            the preconditions for looping in the texturing process.            Including for this aspect, tests were successfully completed            both with hotplate and hotpin as a source of heat. Possibly            the fact helps that the thermal pre-treatment of the yarn            avoids a negative cooling effect of the air expansion in the            texturing nozzle and consequently texturing can be improved            for the warmed-up yarn. Owing to the extremely high            conveyance rate, a part of the heat remains in the yarn even            until it reaches the area of looping.

FIG. 9 shows the effect of a processing medium, be it by hot air, hotvapor or another hot gas, conducted on the conveyed yarn shortly andimmediately subsequently, respectively. The interferences with theprocedure are hence not isolated, but integrated into a combined effectbetween two delivery mechanisms. This means that the yarn is held onlyinitially and at the end, in between there is both the mechanicalapplication of the air and the thermal treatment. The thermal treatmentis conducted on the yarn which is still subjected to tensions in thefilaments and in the yarn, respectively, which are generatedmechanically by compressed air.

FIGS. 10 a through 10 d represent examples for a mechanical and thermaleffect separated in terms of space. The effect takes place spatiallybefore or after the actual texturing, respectively. In this context, thewarming up of the yarn can—if only to a rather limited degree—bepositively used for the texturing. The FIGS. 10 a through 10 d show theuse of the so-called heated and driven godets for the thermal treatmentwith several important possible uses. The temperature reading in thegodet shows for each case if a heated position is present. By analogy, ahotplate or a continuous-flow vapor chamber in accordance with theinvention can also be used for all presentations.

1. A method for treating yarn, comprising: conveying yarn through a yarnduct defined by a texturing nozzle; supplying compressed air into theyarn duct substantially in a conveying direction of the yarn, whereinthe compressed air is supplied at a pressure of more than 4 bar and atan angle of more than 48 degrees with respect to a longitudinal axis ofthe yarn duct, wherein an outlet portion of the yarn duct conicallywidens at an angle of more than about 10 degrees with respect to thelongitudinal axis of the yarn duct so as to generate a supersonic flow.2. The method of claim 1, wherein the compressed air is supplied at anangle of more than 50 degrees with respect to the longitudinal axis ofthe yarn duct.
 3. The method of claim 1, wherein the compressed air issupplied at an angle ranging from 49 degrees to 80 degrees with respectto the longitudinal axis of the yarn duct.
 4. The method of claim 1,wherein the compressed air is supplied at an angle ranging from 50degrees to 70 degrees with respect to the longitudinal axis of the yarnduct.
 5. The method of claim 1, wherein the yarn duct defines acylindrical portion in flow communication with the conically wideningoutlet portion, and the compressed air is supplied into the cylindricalportion.
 6. The method of claim 5, wherein the compressed air issupplied into the cylindrical portion of the yarn duct at a locationwhere opening of the yarn occurs.
 7. The method of claim 5, wherein theangle at which the compressed air is supplied is a function of yarntiter.
 8. The method of claim 1, wherein the compressed air is suppliedat an angle of more than 48 degrees and less than 80 degrees, andwherein intermingling of yarn filaments is substantially avoided.
 9. Themethod of claim 1, further comprising thermally treating the yarn priorto conveying the yarn through the texturing nozzle.
 10. The method ofclaim 9, further comprising thermally treating the yarn after conveyingthe yarn through the texturing nozzle.
 11. The method of claim 1,further comprising thermally treating the yarn after conveying the yarnthrough the texturing nozzle.
 12. An apparatus for treating yarn,comprising: a texturing nozzle defining a yarn duct having an inlet anda longitudinal axis; and at least one compressed air supply orificedisposed so as to supply compressed air into the yarn duct substantiallyin a direction of a conveying direction of yarn through the yarn ductand at an angle of more than about 48 degrees with respect to thelongitudinal axis of the yarn duct, wherein an outlet portion of theyarn duct conically widens at an angle of more than about 10 degreeswith respect to the longitudinal axis of the yarn duct so as to generatea supersonic flow.
 13. The apparatus of claim 12, wherein the at leastone air supply orifice is only one air supply orifice.
 14. The apparatusof claim 12, further comprising three air supply orifices each arrangedso as to supply air to the same location along the longitudinal axis ofthe yarn duct.
 15. The apparatus of claim 14, wherein each of the threeair supply orifices are disposed about 120 degrees apart around the yarnduct.
 16. The apparatus of claim 12, wherein the yarn duct defines acylindrical portion in flow communication with the conically wideningoutlet portion, and the compressed air is supplied into the cylindricalportion.
 17. The apparatus of claim 16, wherein the at least one airsupply orifice is offset from the conically-shaped outlet portion by atleast one diameter of the cylindrical portion.
 18. The apparatus ofclaim 16, wherein the cylindrical portion and the conically-shapedoutlet portion are portions of a nozzle core.
 19. The apparatus of claim18, wherein the nozzle core is configured to be removably inserted intoa texturing nozzle head.
 20. The apparatus of claim 18, furthercomprising a plurality of nozzle cores each formed from a cylindricalportion and a conically-shaped outlet portion of differing dimensions.21. The apparatus of claim 18, wherein the nozzle core is made amaterial resistant to wear.
 22. The apparatus of claim 18, wherein thenozzle core is made of a ceramic material.
 23. The apparatus of claim12, further comprising an impact member disposed at an outlet end of theconically-shaped outlet portion.
 24. The apparatus of claim 23, whereinthe impact member is adjustable so as to alter its position relative tothe outlet end.
 25. The apparatus of claim 19, wherein the texturingnozzle is part of the texturing nozzle head.
 26. The apparatus of claim25, wherein the at least one air supply orifice includes three airsupply orifices.
 27. The apparatus of claim 26, wherein the at least onecompressed air supply is configured to supply compressed air at apressure of more than 4 bar.